1. Technical Field
The present invention relates to a laser light source device and a manufacturing method for manufacturing a laser light source device.
2. Related Art
A high-pressure mercury lamp has been widely used as a light source for illumination of an optical apparatus, such as a projector.
However, the high-pressure mercury lamp has problems in that color reproducibility is limited, instantaneous lighting is difficult, and the life thereof is short.
For this reason, a laser light source device is under development in such a field.
Particularly in a laser light source device with an external resonator structure, a high output can be obtained because light having a specific wavelength can be strengthened by using the external resonator.
However, depending on the wavelength, a sufficient amount of light may not be obtained only by laser oscillation.
Therefore, for example, a technique of oscillating light with a fundamental wavelength, such as infrared laser light, and then converting the infrared laser light into visible light with half of the wavelength by using a wavelength conversion element, such as a second harmonic generator (hereinafter, referred to as an “SHG”), is used.
Within a laser resonator, it is necessary to amplify laser light by leading laser light to oscillate repeatedly to continuously produce stimulated emission.
However, if optical axes deviate from each other even slightly, the laser light cannot sufficiently oscillate, resulting in a state where laser oscillation cannot be performed.
For this reason, in an external resonator type laser light source device, alignment between a laser diode including an emitter and an external resonator is very important. If alignment accuracy is not good, sufficient output cannot be obtained.
For example, as disclosed in Japanese Unexamined Patent Application, First Publication No. 2004-363414, a method for making a reflection face of an external resonant mirror a recessed surface is proposed as a method for suppressing reduction of alignment accuracy caused by thermal lensing effect of a laser excitation medium.
Japanese Unexamined Patent Application, First Publication No. 2004-363414 discloses that even if output laser beams are dispersed or inclined due to the thermal lensing effect of the laser excitation medium, the laser beams converge near the optical axis because the laser beams are reflected from a recessed reflection face of an external resonant mirror, and as a result, a sufficient output can be obtained.
However, there was a limitation in obtaining a high-output laser light even if the alignment accuracy between the laser excitation medium and the external resonant mirror was obtained by using the method disclosed in Japanese Unexamined Patent Application, First Publication No. 2004-363414.